Dispersion pass

V-Ray V-Ray for Maya V-Ray for Maya :: General
1

Hi all

Is it possible to output a pass with the dispersion info only?

Cheers

2

Not directly, but I guess you can extract only the dispersion info in i.e. Nuke by subtracting the regular refraction out of the dispersed refraction. This would require a second render, however.

3

Problem is that there is a bug with Dispersion, when you use the Translucency set to ‘Volumetric’.
https://forums.chaos.com/forum/v-ray-for-maya-forums/v-ray-for-maya-problems/1182140-dispersion-issue

4

I see… Well, another way is to render the translucency separately. I tried this and it seems to work well, however, you will need three refraction passes (refraction only, dispersion only, and translucency only). Combining the Dispersion only and Translucency only will give you double regular refractions, hence the need for a refraction pass to subtract with. A bit tedious, I know, but it works. Check attach files, Nuke comp included.
1186971.7z (3.08 MB)

5

Thanks very much.

Which shader settings are you using for each pass?

6

Here’s the Maya scene.
For refractions only: White refraction; Dispersion = off; SSS Amount = 0
For translucency only: White refraction; Dispersion = off; SSS Amount = 1
For dispersion only: White refraction, Dispersion = on; SSS Amount = 0
test.7z (10.6 KB)

7

Thanks for the file.

I get colour management errors on the Maya file - on Maya 2023

Screenshot 2023-08-04 at 16.51.17.jpg
Screenshot 2023-08-04 at 16.51.17.jpg2224×636 145 KB

8

I just had an OCIO config set up in the color management options. Either relink one from your own PC or use the Maya native color management. Either way, it won’t matter for the purposes of the sample setup.